1git-interpret-trailers(1) 2========================= 3 4NAME 5---- 6git-interpret-trailers - add or parse structured information in commit messages 7 8SYNOPSIS 9-------- 10[verse] 11'git interpret-trailers' [<options>] [(--trailer <token>[(=|:)<value>])...] [<file>...] 12'git interpret-trailers' [<options>] [--parse] [<file>...] 13 14DESCRIPTION 15----------- 16Help parsing or adding 'trailers' lines, that look similar to RFC 822 e-mail 17headers, at the end of the otherwise free-form part of a commit 18message. 19 20This command reads some patches or commit messages from either the 21<file> arguments or the standard input if no <file> is specified. If 22`--parse` is specified, the output consists of the parsed trailers. 23 24Otherwise, this command applies the arguments passed using the 25`--trailer` option, if any, to the commit message part of each input 26file. The result is emitted on the standard output. 27 28Some configuration variables control the way the `--trailer` arguments 29are applied to each commit message and the way any existing trailer in 30the commit message is changed. They also make it possible to 31automatically add some trailers. 32 33By default, a '<token>=<value>' or '<token>:<value>' argument given 34using `--trailer` will be appended after the existing trailers only if 35the last trailer has a different (<token>, <value>) pair (or if there 36is no existing trailer). The <token> and <value> parts will be trimmed 37to remove starting and trailing whitespace, and the resulting trimmed 38<token> and <value> will appear in the message like this: 39 40------------------------------------------------ 41token: value 42------------------------------------------------ 43 44This means that the trimmed <token> and <value> will be separated by 45`': '` (one colon followed by one space). 46 47By default the new trailer will appear at the end of all the existing 48trailers. If there is no existing trailer, the new trailer will appear 49after the commit message part of the output, and, if there is no line 50with only spaces at the end of the commit message part, one blank line 51will be added before the new trailer. 52 53Existing trailers are extracted from the input message by looking for 54a group of one or more lines that (i) is all trailers, or (ii) contains at 55least one Git-generated or user-configured trailer and consists of at 56least 25% trailers. 57The group must be preceded by one or more empty (or whitespace-only) lines. 58The group must either be at the end of the message or be the last 59non-whitespace lines before a line that starts with '---' (followed by a 60space or the end of the line). Such three minus signs start the patch 61part of the message. See also `--no-divider` below. 62 63When reading trailers, there can be whitespaces after the 64token, the separator and the value. There can also be whitespaces 65inside the token and the value. The value may be split over multiple lines with 66each subsequent line starting with whitespace, like the "folding" in RFC 822. 67 68Note that 'trailers' do not follow and are not intended to follow many 69rules for RFC 822 headers. For example they do not follow 70the encoding rules and probably many other rules. 71 72OPTIONS 73------- 74--in-place:: 75 Edit the files in place. 76 77--trim-empty:: 78 If the <value> part of any trailer contains only whitespace, 79 the whole trailer will be removed from the resulting message. 80 This applies to existing trailers as well as new trailers. 81 82--trailer <token>[(=|:)<value>]:: 83 Specify a (<token>, <value>) pair that should be applied as a 84 trailer to the input messages. See the description of this 85 command. 86 87--where <placement>:: 88--no-where:: 89 Specify where all new trailers will be added. A setting 90 provided with '--where' overrides all configuration variables 91 and applies to all '--trailer' options until the next occurrence of 92 '--where' or '--no-where'. 93 94--if-exists <action>:: 95--no-if-exists:: 96 Specify what action will be performed when there is already at 97 least one trailer with the same <token> in the message. A setting 98 provided with '--if-exists' overrides all configuration variables 99 and applies to all '--trailer' options until the next occurrence of 100 '--if-exists' or '--no-if-exists'. 101 102--if-missing <action>:: 103--no-if-missing:: 104 Specify what action will be performed when there is no other 105 trailer with the same <token> in the message. A setting 106 provided with '--if-missing' overrides all configuration variables 107 and applies to all '--trailer' options until the next occurrence of 108 '--if-missing' or '--no-if-missing'. 109 110--only-trailers:: 111 Output only the trailers, not any other parts of the input. 112 113--only-input:: 114 Output only trailers that exist in the input; do not add any 115 from the command-line or by following configured `trailer.*` 116 rules. 117 118--unfold:: 119 Remove any whitespace-continuation in trailers, so that each 120 trailer appears on a line by itself with its full content. 121 122--parse:: 123 A convenience alias for `--only-trailers --only-input 124 --unfold`. 125 126--no-divider:: 127 Do not treat `---` as the end of the commit message. Use this 128 when you know your input contains just the commit message itself 129 (and not an email or the output of `git format-patch`). 130 131CONFIGURATION VARIABLES 132----------------------- 133 134trailer.separators:: 135 This option tells which characters are recognized as trailer 136 separators. By default only ':' is recognized as a trailer 137 separator, except that '=' is always accepted on the command 138 line for compatibility with other git commands. 139+ 140The first character given by this option will be the default character 141used when another separator is not specified in the config for this 142trailer. 143+ 144For example, if the value for this option is "%=$", then only lines 145using the format '<token><sep><value>' with <sep> containing '%', '=' 146or '$' and then spaces will be considered trailers. And '%' will be 147the default separator used, so by default trailers will appear like: 148'<token>% <value>' (one percent sign and one space will appear between 149the token and the value). 150 151trailer.where:: 152 This option tells where a new trailer will be added. 153+ 154This can be `end`, which is the default, `start`, `after` or `before`. 155+ 156If it is `end`, then each new trailer will appear at the end of the 157existing trailers. 158+ 159If it is `start`, then each new trailer will appear at the start, 160instead of the end, of the existing trailers. 161+ 162If it is `after`, then each new trailer will appear just after the 163last trailer with the same <token>. 164+ 165If it is `before`, then each new trailer will appear just before the 166first trailer with the same <token>. 167 168trailer.ifexists:: 169 This option makes it possible to choose what action will be 170 performed when there is already at least one trailer with the 171 same <token> in the message. 172+ 173The valid values for this option are: `addIfDifferentNeighbor` (this 174is the default), `addIfDifferent`, `add`, `replace` or `doNothing`. 175+ 176With `addIfDifferentNeighbor`, a new trailer will be added only if no 177trailer with the same (<token>, <value>) pair is above or below the line 178where the new trailer will be added. 179+ 180With `addIfDifferent`, a new trailer will be added only if no trailer 181with the same (<token>, <value>) pair is already in the message. 182+ 183With `add`, a new trailer will be added, even if some trailers with 184the same (<token>, <value>) pair are already in the message. 185+ 186With `replace`, an existing trailer with the same <token> will be 187deleted and the new trailer will be added. The deleted trailer will be 188the closest one (with the same <token>) to the place where the new one 189will be added. 190+ 191With `doNothing`, nothing will be done; that is no new trailer will be 192added if there is already one with the same <token> in the message. 193 194trailer.ifmissing:: 195 This option makes it possible to choose what action will be 196 performed when there is not yet any trailer with the same 197 <token> in the message. 198+ 199The valid values for this option are: `add` (this is the default) and 200`doNothing`. 201+ 202With `add`, a new trailer will be added. 203+ 204With `doNothing`, nothing will be done. 205 206trailer.<token>.key:: 207 This `key` will be used instead of <token> in the trailer. At 208 the end of this key, a separator can appear and then some 209 space characters. By default the only valid separator is ':', 210 but this can be changed using the `trailer.separators` config 211 variable. 212+ 213If there is a separator, then the key will be used instead of both the 214<token> and the default separator when adding the trailer. 215 216trailer.<token>.where:: 217 This option takes the same values as the 'trailer.where' 218 configuration variable and it overrides what is specified by 219 that option for trailers with the specified <token>. 220 221trailer.<token>.ifexists:: 222 This option takes the same values as the 'trailer.ifexists' 223 configuration variable and it overrides what is specified by 224 that option for trailers with the specified <token>. 225 226trailer.<token>.ifmissing:: 227 This option takes the same values as the 'trailer.ifmissing' 228 configuration variable and it overrides what is specified by 229 that option for trailers with the specified <token>. 230 231trailer.<token>.command:: 232 This option can be used to specify a shell command that will 233 be called to automatically add or modify a trailer with the 234 specified <token>. 235+ 236When this option is specified, the behavior is as if a special 237'<token>=<value>' argument were added at the beginning of the command 238line, where <value> is taken to be the standard output of the 239specified command with any leading and trailing whitespace trimmed 240off. 241+ 242If the command contains the `$ARG` string, this string will be 243replaced with the <value> part of an existing trailer with the same 244<token>, if any, before the command is launched. 245+ 246If some '<token>=<value>' arguments are also passed on the command 247line, when a 'trailer.<token>.command' is configured, the command will 248also be executed for each of these arguments. And the <value> part of 249these arguments, if any, will be used to replace the `$ARG` string in 250the command. 251 252EXAMPLES 253-------- 254 255* Configure a 'sign' trailer with a 'Signed-off-by' key, and then 256 add two of these trailers to a message: 257+ 258------------ 259$ git config trailer.sign.key "Signed-off-by" 260$ cat msg.txt 261subject 262 263message 264$ cat msg.txt | git interpret-trailers --trailer 'sign: Alice <alice@example.com>' --trailer 'sign: Bob <bob@example.com>' 265subject 266 267message 268 269Signed-off-by: Alice <alice@example.com> 270Signed-off-by: Bob <bob@example.com> 271------------ 272 273* Use the `--in-place` option to edit a message file in place: 274+ 275------------ 276$ cat msg.txt 277subject 278 279message 280 281Signed-off-by: Bob <bob@example.com> 282$ git interpret-trailers --trailer 'Acked-by: Alice <alice@example.com>' --in-place msg.txt 283$ cat msg.txt 284subject 285 286message 287 288Signed-off-by: Bob <bob@example.com> 289Acked-by: Alice <alice@example.com> 290------------ 291 292* Extract the last commit as a patch, and add a 'Cc' and a 293 'Reviewed-by' trailer to it: 294+ 295------------ 296$ git format-patch -1 2970001-foo.patch 298$ git interpret-trailers --trailer 'Cc: Alice <alice@example.com>' --trailer 'Reviewed-by: Bob <bob@example.com>' 0001-foo.patch >0001-bar.patch 299------------ 300 301* Configure a 'sign' trailer with a command to automatically add a 302 'Signed-off-by: ' with the author information only if there is no 303 'Signed-off-by: ' already, and show how it works: 304+ 305------------ 306$ git config trailer.sign.key "Signed-off-by: " 307$ git config trailer.sign.ifmissing add 308$ git config trailer.sign.ifexists doNothing 309$ git config trailer.sign.command 'echo "$(git config user.name) <$(git config user.email)>"' 310$ git interpret-trailers <<EOF 311> EOF 312 313Signed-off-by: Bob <bob@example.com> 314$ git interpret-trailers <<EOF 315> Signed-off-by: Alice <alice@example.com> 316> EOF 317 318Signed-off-by: Alice <alice@example.com> 319------------ 320 321* Configure a 'fix' trailer with a key that contains a '#' and no 322 space after this character, and show how it works: 323+ 324------------ 325$ git config trailer.separators ":#" 326$ git config trailer.fix.key "Fix #" 327$ echo "subject" | git interpret-trailers --trailer fix=42 328subject 329 330Fix #42 331------------ 332 333* Configure a 'see' trailer with a command to show the subject of a 334 commit that is related, and show how it works: 335+ 336------------ 337$ git config trailer.see.key "See-also: " 338$ git config trailer.see.ifExists "replace" 339$ git config trailer.see.ifMissing "doNothing" 340$ git config trailer.see.command "git log -1 --oneline --format=\"%h (%s)\" --abbrev-commit --abbrev=14 \$ARG" 341$ git interpret-trailers <<EOF 342> subject 343> 344> message 345> 346> see: HEAD~2 347> EOF 348subject 349 350message 351 352See-also: fe3187489d69c4 (subject of related commit) 353------------ 354 355* Configure a commit template with some trailers with empty values 356 (using sed to show and keep the trailing spaces at the end of the 357 trailers), then configure a commit-msg hook that uses 358 'git interpret-trailers' to remove trailers with empty values and 359 to add a 'git-version' trailer: 360+ 361------------ 362$ sed -e 's/ Z$/ /' >commit_template.txt <<EOF 363> ***subject*** 364> 365> ***message*** 366> 367> Fixes: Z 368> Cc: Z 369> Reviewed-by: Z 370> Signed-off-by: Z 371> EOF 372$ git config commit.template commit_template.txt 373$ cat >.git/hooks/commit-msg <<EOF 374> #!/bin/sh 375> git interpret-trailers --trim-empty --trailer "git-version: \$(git describe)" "\$1" > "\$1.new" 376> mv "\$1.new" "\$1" 377> EOF 378$ chmod +x .git/hooks/commit-msg 379------------ 380 381SEE ALSO 382-------- 383linkgit:git-commit[1], linkgit:git-format-patch[1], linkgit:git-config[1] 384 385GIT 386--- 387Part of the linkgit:git[1] suite